ML20245H770
| ML20245H770 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 02/21/1989 |
| From: | Drawbridge B YANKEE ATOMIC ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-1275 BYR-89-024, BYR-89-24, GL-88-14, IEIN-87-028, IEIN-87-28, NUDOCS 8903030472 | |
| Download: ML20245H770 (5) | |
Text
" YANKEEATOMICELECTRIC COMPANY
'Q"* @?g1ll*;"l" p
580 Main Street, Bolton, Massachusetts 01740-1398 February 21,'1989 BYR 89-024
. United States Nuclear Regulatory Commission Document Control Desk Washington', DC 20555.
References:
(a) License No. DPR-3 (Docket No. 50-29)
I (b) Letter, NYR 88-235, USNRC to YAEC, " Instrument Air. Supply
-System Problems Affecting Safety-Related Equipment (Generic Letter 88-14)," dated August 8, 1988 (c) NRC Information Notice 87-28, " Air Systems Problems at U.S. Light Water Reactors," dated June 22, 1987
Subject:
Response to Generic Letter 88-14
Dear Sir:
Generic Letter 88-14, Reference (b), requested Yankee to review NUREG-1275 (Volume 2) and to perform a design and operations verification of the Instrument Air System.
In addition, Generic Letter 88-14 requested Yankee to provide a discussion of our program for maintaining proper instrument air quality. The attachment to this letter provides the information requested by Generic Letter 88-14.
'We trust this information is satisfactory; however, if you have any questions, please contact us.
Very truly yo rs,
/
Y E ATOMI ELECTRIC COMPANY Abu B. L. Dr (wbridge Vice Presiden and Manager of Operations BLD/b11/0184v Attachment cc: USNRC Region I USNRC Resident Inspector, YNPS COMMONWEALTH OF MASSACHUSETTS)
)ss MIDDLESEX COUNTY
)
Then personally appeared before me, B. L. Drawbridge, who, being duly sworn, did state that he is Vice President and Manager of Operations, that he is duly authorized to execute and file the foregoing document in the name and h0f on the behalf of Yankee Atomic Electric Company, and that the statements therein are true to the best of his knowledge and belief.
8903030472 890221 Helen D. Sammarco Notary Public PDR ADOCK 05000029 P
PDC My Commission Expires November 7, 1991 h
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ATTACHMENT
!O' Response to Generic Lett'er 88-14 L
N Generic Letter 88-14! discusses the concerns th'e NRC has with Instrument Air-l System problems, and their affect-on safety-related' equipment. The. Generic
- ; Letter references NUREG-1275, Volume 2, " Operating Feedback Report
' Air
-Systems Problems J' which was issued earlier by: Information Notice.87-28, Reference (c). : NUREG-1275 ' reviewed significant operating-events involving 1
failures of safety-related' systems that resulted from problems-with Instrument
~
' Air. Systems. lit. concluded that~these events were significant enough to warrant additional NRC.and-industry. attention.- Concern for.these events
- formed the basis'forJ' issuing Generic' Letter 88-14.1 As part of the eval'ation of Information Notice 87-28, NUREG-1275 was reviewed D
u in detail for appliccbilitysto the Yankee Nuclear Power Station (YNPS). 'This Jreview focused firstfon a. comparison of the major plant systems. identified'in:
NUREG-1275 which utilize instrument air to those at the YNPS.
In the course
'of this seview, it became apparent-that the YNPS does not use instrument air
.in plant safety-related systems as. extensively as most plants.
In' fact, the use of instrument air in safety-related systems at YNPS is very' limited. All of the air-related incidents that resulted in safety-system. failures described
=in NUREG-1275 were. reviewed to determine if an air-related problem;could cause a similar event at the YNPS.
It was determined that almost all of these events were not applicable to the.YNPS, since the similar. equipment.and systems at the YNPS do not-use instrument air. The events.that were applicable to YNPS were. evaluated and were determined not to cause similar
- problems at YNPS.
Based on this review, the NRC concerns that led to the issuance of Generic Letter 88-14 are'not as critical'to the safe operation of the YNPS. However, Yankee is interested in improving the reliability of the YNPS Instrument Air System since.it.does impact plant operation..Therefore, the recommendations of NUREG-1275 were reviewed in detail to determine what could be done to
' improve. Instrument Air. System and. plant performance. This was ongoing when Generic Letter 88-14 was received.
The following is the response to.the specific.information request by Generic
-Letter 88-14:
Item 1 - Instrument Air Quality Verification by test that actual instrument-air quality is consistent with the manufacturer's recommendations for individual components served.
v
Response
The manufacturers of the air-operated safety-related components at YNPS were contacted.to determine the air quality requirements of'their components. The common response was " clean, oil-free air."
One manufacturer, however, requires that the air meet the current industry standard (ISA S7.3).
Therefore, YNPS tested the instrument air against the requirements of this standard. _ _ _ _ - - _ _ _ _ - - _ _ _ _ - _ - _ _ _ _ _
W 79'
(
o-I ATTACHMENT L
(continued) l Response to Generic Letter 88-14 During the.recent refueling, YNPS tested the instrument air for hydrocarbon content and particle size. The resultant hydrocarbon content from this test was well below that of the standard; however, the resultant particle size was greater than the size allowed by the standard. The YNPS has never experienced an air-operated equipment failure due to air particulate, and the components requiring that air meet the current standard will either fail safe or can be manually bypassed. The containment isolation valves will fail _ closed in the event of a loss of instrument air. The steam driven emergency feedwater pump
'Is manually initiated locally.
In a loss of instrument air event the steam regulating valve can be manually bypassed, therefore no immediate action is necessary..However, a further evaluation of the Instrument Air System filtering process will be conducted, and changes will be made to assure that equipment requirements will be met.- The dew point was not tested since it is currently monitored'under plant procedures. The procedural dew point requirement meets the current standard.
In addition to the above mentioned evaluation, the hydrocarbon content and particle size test requirements will be included in a YNPS surveillance procedure. 'These new tests, combined with the current dew point test, will have YNPS performing the full supplement of air quality tests. These tests, along with YNPS procedures for maintaining the air dehydrators, the air filters, and the air compressors, will help assure proper instrument air quality at YNPS.
The evaluation of the Instrument Air System filtering process will be completed by June 30, 1989. The surveillance procedure will be updated to incorporate hydrocarbon content and particle size requirements by June 30, 1989.
Item 2 - Maintenance and Operations Training Verification that maintenance practices, emergency procedures, and training are adequate to ensure that safety-related equipment will function as intended on loss of instrument air.
Response
The Instrument Air System training for both maintenance personnel and plant operators was reviewed as a result of Information Notice 87-28.
Plant operators are currently trained in the use of the loss of air emergency procedures and on the importance of the Instrument Air System. The existing emergency procedures and related operator training are adequate, and require no revisions.
In contrast, maintenance personnel do not currently receive training regarding the importance of the Instrument Air System. However, the
" Power Plant Fundamentals" course provided to all new maintenance personnel will be revised to include the following: l 1
e ATTACHMENT
'(continued)
Response to Generic Letter 88-14 1.
The interaction of the Instrument Air System with safety class systems.
2.
Identification of safety systems rendered inoperable on loss of instrument air.
3.
Identification of types of instrument air contamination and the effects of each (e.g., moisture, oil and hydrocarbons, and particulate).
4.
Maintenance practices to minimize contamination when working on the Instrument Air System.
The revision to the training program will be completed by June 30, 1989.
In addition, Instrument Air System training will be.given to all existing 1
maintenance personnel via the Continuing Maintenance Training Program. This training will be completed by December 31, 1989. Training in these and related topics will sensitize maintenance personnel to the importance of the Instrument Air System.
Item 3 - Instrument Air System Design Verification that the design of the entire Instrument Air System, including air or other pneumatic accumulators, is in accordance with its intended function, including verification by test that air-operated, safety-related components will perform as expected in accordance with all design basis events, including a loss.of the normal Instrument Air System. This design verification should include an analysis of current air-operated component failure positions to verify that they are correct for assuring required safety functions.
Response
To complete the design verification, the following tests were performed at YNPS:
1.
Back-up Nitrogen Accumulator Capacity Test - This test was performed to support the calculation of the operation time for the one required back-up accumulator.
2.
Individual Component Loss of Instrument Air Tests - These tests were performed to verify the expected response of components during a " Loss of Instrument Air" event.
Under the current design basis, YNPS does not require the use of any back-up nitrogen accumulators during a " Loss of Instrument Air" event. However, as a result of Yankee's evaluation of the station blackout rule (10CFR50.63), YNPS will require the use of the back-up nitrogen accumulator in the Emergency Feedwater System. The required operation time of l 1
1
{
ATTACHMENT (continued)
Response to Generic Letter 88-14 1
the accumulator will be one hour. During the most recent YNP5 refueling, the j
accumulator operation time was determined to be 0.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
This time was 4
determined by using the current YNPS " Loss of Instrument Air Procedures" and i
i correlating the results with the minimum acceptable accumulator pressure currently specified in plant procedures. A procedural change is required to q
assure that the accumulator operation time will be greater than the required one hour. This procedural change will raise the minimum acceptable accumulator pressure to assure adequate accumulator volume and/or require isolating non-essential components supplied by the same accumulator during a loss of instrument air event. The procedural change to increase the operation time of the accumulator will be completed by April 15, 1989, which is consistent with the schedule required by the station blackout rule.
An individual loss of air test was performed on 15 valves, which were assumed to fail in a certain manner during a loss of air event. All 15 valves operated as expected. Containment isolation valves were not tested as part of this effort, since they undergo routine surveillance testing, which simulates a loss of air event.
This verification of the design of the Instrument Air System has shown that all air-operated components at the YNPS will perform as assumed in the current
" Loss of Instrument Air" Procedure.
In addition, it also verified that all air-operated components at the YNPS will perform their intended safety function under the current design basis.
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